It is planned to evaluate the specific stereochemical requirements of hormone receptor sites and the relationship between the requirements and the ability to transfer specific messages. It is proposed to prepare steroidal hormones and sesquiterpene lactones modified by substituent and by stereochemistry and to have their antitumor and other biological activities determined. The proposed steroidal hormone research has as its basis the preparation of fusidic acid and shionone tetracyclic systems, systems which are biogenetically related to natural steroids. The proposed sesquiterpene research has as its basis the systhesis of compounds related to the antitumor sesquiterpene lactone vernolepin. The general eudalene nucleus possessing the requisite functional groups will be prepared.